Science news this week: An enigmatic human relative, dark matter discovery and mysterious lights in the sky during nuclear weapons tests Live ScienceEarly hominin Australopithecus afarensis may not be our human ancestor after all Natural History MuseumNew finds shed light on diet and locomotion in Australopithecus deyiremeda Nature‘Lucy’ Was Neighbors With an Even Older Human Ancestor, Fossils Reveal ScienceAlertA fossilized foot found 15 years ago belonged to enigmatic human relative that lived alongside Lucy, scientists say Live Science